Working Hot Air Balloon

At the top of the gondola, place a round piece of cork, about 2 cm in diameter. On top of this, place a bottle cap (I made mine the size of an Estrella Galicia beer cap), and on top of the cap, a circular piece of hexamine fire starter.

For making the balloon, it is recommended to use thin, high-density polyethylene (HDPE) bags (the typical translucent garbage bags), as they offer the best weight-to-watertightness ratio. The sail is constructed by assembling segments cut with a parabolic template to ensure an efficient spherical or oval shape. The panels should be joined by overlapping the edges and sealing them with light adhesive tape or contact cement stick, avoiding excess adhesive to prevent adding to the overall weight. It is essential to reinforce the lower opening of the balloon with a ring of thin cardboard or tape to distribute the tension of the guy wires connecting to the printed gondola, maintaining a separation of at least 25 cm to protect the material from rising heat.